This study of brain mechanisms in phonation of rhesus monkey will use behavioral techniques to obtain discriminative phonation and physiological techniques to explore the mechanisms which govern the process. A test for hemispheric lateralization of phonatory control will be conducted utilizing intra-carotid injection of sodium amytal. Evidence obtained from testing for lateralization of phonatory control will clarify the status of the neural systems which underlie complex phonation. Subsequent brain lesion studies will identify the structures which participate together with the anterior cingulate cortex (a region already known to be important for phonation in humans as well as monkeys). Coordinate analysis of neural unit activity in these phonation-related structures will describe how information is processed and transformed in phonatory activity. Information from these investigations will foster a clearer understanding of brain function in communicative disorders.